Optical Calibration and Spectroscopy Laboratory

Optical interferometer and camera calibration systems provide a means for researchers to calibrate sensor performance and reference frames that are utilised in the development and characterisation of optical space systems. The laboratory also investigates quantities methods in radiative transfer and spectroscopy using custom developed software tools including the Genspect radiative transfer tool.

Laser Calibration of Argus Instrument, YorkU.

Selected Publications 

2007    B. M. Quine, V. Tarasyuck, H. Mebrahtu and R. Hornsey, Determining Star Image Location: A new Sub-Pixel Interpolation Technique to Process Image Centroids, Computer Physics Communications, 177, 700-706.

Abstract: We develop a theoretical methodology to estimate the location of star centroids in images recorded by CCD and active pixel sensors. The approach may be generalized to other applications were point-sources must be located with high accuracy. In contrast with other approaches, our technique is suitable for use with non-100% fill ratio sensors. The approach is applied experimentally to two camera systems employing sensors with fill-ratios of approximately 50%. We describe experimental approaches to implement the new paradigm and characterize centroid performance using laboratory targets and against real night-sky images. Applied to a conventional CCD camera, a centroid performance of 11.6 times the raw pixel resolution is achieved. Applied to a camera employing an active-pixel sensor a performance of 12.8 is demonstrated. The approach enables the rapid development of autonomous star-camera systems without the extensive characterizations required to derive polynomic fitting coefficients employed by traditional centroid algorithms.

2007    M. Toohey, B. M. Quine, K. Strong, P. F. Bernath, C. D. Boone, A. I. Jonsson,  C. T. McElroy, K. A. Walker and D. Wunch. Balloon-Borne radiometer measurement of Northern Hemisphere mid-latitude stratospheric HNO3 profiles spanning 12 years, Atmos. Chem. Phy. Discuss., 7, 11561-11586.

2005    Jagpal, R.; Quine, B.; Caldwell, J., Separating Extrasolar Planetary Photons from Stellar Ones, American Astronomical Society, DPS meeting 37, 31.07; Bulletin of the American Astronomical Society, Vol. 37, p.684.

Abstract: Spatial resolution of the light reflected by extra-solar planets from the light of their parent stars is financially and technically challenging. However, the properties of one of the most common types of extra-solar planets found to date, "hot Jupiters", suggest another approach to their study. The majority of extrasolar planets have been discovered through an analysis of stellar spectra in order to detect velocity variations induced by the presence of large, close-orbiting planets. However, the close proximity of hot Jupiters to their stars results in detectable brightness levels of reflected planetary light, about 10,000 times Jupiter's reflected light. Thus, the spatially unresolved stellar spectra also contain light reflected directly from the visible level of these planetary bodies. The orbital velocities and resultant Doppler shifts of the planets are about 1000 times greater than the stellar "wobble". The magnitude and phase of the Doppler shifts of the planets can be found from the original stellar wobble. We are investigating practical considerations and methodology needed to extract planetary information from the known Doppler variation of the reflected planetary signal from that of the parent star, in the presence of noise. Our approach employs a Monte-Carlo simulation of the combined star-planet observation in order to predict accurately the time variation of the expected combined spectra. We propose to use this analysis to develop a means to separate a planetary spectrum from the stellar one in order to investigate planetary inhomogeneity, including albedo variations across the disk of the planet, if they exist, and to determine detailed planetary spectra in order to infer atmospheric composition.

2002    B. M. Quine and J. R. Drummond. GENSPECT: A Line-by-Line Code with Selectable Interpolation Error Tolerance, J. Quant. Spectrosc. & Radiat. Transfer, 74, pp. 147-165.